This invention relates to improvements in devices for stretching silkscreen for use in the silkscreening process, and more particularly to a simplified, universal, low-cost stretching device which is quick and easy to use.
Historically, the silkscreening process has involved a labor-intensive and highly skilled task of securing the screen on a stretching frame and applying the appropriate tension to the screen to achieve a clear and precise image during the transfer, particularly when using multi-colors.
Over the years, improvements have been made which reduced the skill and time involved, including, tensionable frames wherein the sides of the frames were of elongated cylinders which could be rotated about their axis, applying tension the silkscreen fabric, and then fastened in place to the adjacent cornerpiece once the appropriate tension had been reached.
Further improvements included a tensioning of the frame through the use of hydraulic or pneumatic means that either replaced mechanical means or augmented the mechanical means.
Still another step forward was realized when the silkscreen was pre-cut to size, including an allowance for the bending of the side frame during the tensioning process. This pre-cutting of the fabric and placing splines on the edges allowed the screen to be quickly snapped into pre-provided slots in the stretching frame sides, but also allowed the user to purchase exactly the amount of fabric necessary, and further allowed the tensioning to be achieved through the use of calibration means, which assured that the same tension would be applied to the screens each time used. When using a pre-cut screen, the operator need only read the calibration number provided for that screen and replicate that number on a stretching device which includes calibration.
Prior art references known to the present inventor include:
U.S. Pat. No. 3,601,912, which discloses an early woven screen-stretching frame;
U.S. Pat. No. 4,525,909, granted to Newman, Jul. 2, 1985, discloses an improved method of securing the fabric to the stretching frame;
U.S. Pat. No. 5,113,611, granted to Rosson, May 19, 1992, discloses a method and apparatus for stretching silkscreen wherein the silkscreen frame itself is expanded to stretch the screen;
U.S. Pat. No. 5,443,003, granted to Larson, Aug. 22, 1995, discloses a method and apparatus for pre-cutting a piece of fabric, then attaching said fabric to a spline which is then snapped into the sides of a silkscreen-stretching device;
U.S. Pat. No. 5,488,901, granted to Hruska, Feb. 6, 1996, discloses a silkscreen-stretching device including lever-enhanced pneumatic or hydraulic cylinders for performing the stretching upon a stretching frame secured to the upper portion of the table;
U.S. Pat. No. 5,676,052, Wegrzyn et al., Oct. 14, 1997, discloses an apparatus for securing a frame-mounted screen to a table and then using the human torso as a means of placing tension of the screen;
U.S. Pat. No. 5,913,263, granted to Hruska, Jun. 22, 1999, discloses yet another method of using hydraulics or pneumatics for tightening the screen; and
U.S. Pat. No. 5,937,753, granted to McKeever, discloses yet another apparatus for applying the appropriate tension to the screen which is secured to a frame.
With the above noted prior art in mind, it is a feature of the present invention to provide a silkscreen tension device which is inexpensive and easy to operate.
Another feature of the present invention is the provision of a silkscreen-stretching device which requires minimal skill of the operator and yields consistent results.
Still another feature of the present invention lies in the fact that the current device is readily adapted to different fabrics.
A further feature of the present invention is found in the additional support provided to the frame during the stretching process to reduce the torque on the frame elements and thus reducing the possibility of fatigue.